On Thursday, Broward County authorities listed 17 premeditated murder charges against Nikolas Cruz, the 19-year-old who allegedly opened fire in an attack at Marjory Stoneman Douglas High School in Florida.

A court, according to Business Insider, will try Cruz as an adult and could give him the death penalty if the jury unanimously recommends that.

Cruz’s alleged rampage left 16 injured and 17 dead, according to the Sun-Sentinel.

Although Cruz’s motive is currently unknown, multiple reports surfaced about his allegedly troubling behavior.

During a news conference on Wednesday, Broward County Sheriff Scott Israel indicated that authorities investigated Cruz’s social media presence and found disturbing content.

“Some of the things that have come to mind are very, very disturbing,” he said.

As CNN reported, Cruz posted violence-related content on social media. On Instagram, he posted photos of himself with a pistol and long knives.

“I wanna die Fighting killing s**t ton of people,” he reportedly said in a comment on an online video.

In a Thursday morning tweet, President Donald Trump said “so many signs” pointed to Cruz having mental health issues:

So many signs that the Florida shooter was mentally disturbed, even expelled from school for bad and erratic behavior. Neighbors and classmates knew he was a big problem. Must always report such instances to authorities, again and again!